There are a lot of things about the Baileys Women's Prize for Fiction that it's easy to sneer at. The fact that it's sponsored by a company whose past advertisements include close-up shots of women's lips (glitter and gloss covered, no drink in sight, 2008), a pair of leerily suggestive glasses with bobbing ice-cube nipples (tagline: 'The Milk of Ireland', 2001) and, more recently, a blonde holding a glass over a cityscape balcony, captioned: 'be a girl with a mind, a woman with attitude and a lady with class'. Or the fact that this line might have, one supposes, helped Baileys become the 'ideal choice as … partner' when the Women's Prize for Fiction was seeking a new sponsor – let's not be coy – in 2013. Or that the story of the Prize's inception, as written on its new, Baileys-colour-scheme website, goes in one breath from extolling the necessity of keeping 'education, literary and research initiatives as integral to the Prize' to cheerfully adding that the new award 'would be fun!'

Or one could – and many have and do – sneer at the fact it's a prize for women. The very premise has not escaped criticism, particularly in recent years. Last November, novelist AS Byatt was quoted in The Times arguing that the award is now superfluous: women, she suggests, have possibly "taken to writing better novels" and certainly now receive "fair treatment". Notions of sudden improvement aside – the litany of pre-21st century women novelists of great talent is too easy to recite – one can see why Byatt might believe as much. Earlier this year, twice Man Booker winner Hilary Mantel became the only living author to have a portrait in the British Library, with Nick Lord's depiction of her, pen in hand, joining paintings of Shakespeare, TS Eliot and Virginia Woolf. Herself a Women's Prize nominee, Mantel has also won the David Cohen Prize, two Costa Book Awards and 'UK Author of the Year' twice at the Specsavers National Book Awards. In an age when the most vaunted, most publicised novelist of our generation is a woman, when she is painted, and adapted for stage, and repeatedly at the head of fiction shortlists, do we really need a women's only prize?

From a feminist perspective it may seem spurious. Germaine Greer famously stated of the award that there would soon be a fiction prize for "writers with red hair", and literary figures from Byatt to former Times-editor Simon Jenkins have dubbed the Prize "sexist". If I were Byatt, I too would be annoyed to find myself compared not to all novelists but only to the women writers, just as I am annoyed to ever hear the phrase 'one of the greatest woman novelists' - why not just 'greatest novelists'? - or find weeks on 'women's history' and 'women's writing' on undergraduate introductory modules. There is something somehow infantilising about being the best of the women; a delicate honour which has overtones of that irritating, compartmentalising phrase, 'not bad for a girl'. Commenting on the Baileys tagline quoted above, Branding Magazine's Katrina Radic suggested that such sentiments degrade women "instead of celebrating them", with the logic that "if women… actually are witty, beautiful and strong, Baileys telling them to be the same is pointlessly contradictory". The Baileys Prize might easily be interpreted the same way: if women are genuinely equal novelists to men, then surely a prize celebrating them specifically need not exist; ergo, its very existence suggests that they simply are not. Certainly the odd assumption that women compete only with other women and not with everyone in their field is prolific - too prolific, surely, for such a visible object in the literary landscape to perpetuate it. To ringfence women's novels is surely to contain them as much as it is to ensure their safety; locking them up in a separate longlist and telling them it's for their own good, leaving everything else the domain of men.

But to argue this is to misunderstand what literary prizes are really for. Not what they profess to be for – judging the best writer – but what they're really for.

The power of the literary award does not lie in a panel of judges naming you the best writer; it lies in the publicity. Writing for The Guardian Books Blog last year, Observer associate editor and ex-editor-in-chief of Faber & Faber Robert McCrum diagnosed today's literary culture as one "where prizes, as much as reviews, make the running, and where big prizes become themselves a cultural event of unprecedented consequence". The rise of Mantel is a case in point: "you only have to watch [her fate] (post-Booker and post-Costa) to see the impact of prize-winning on one blameless writer unfamiliar with the rules of life in the spotlight". Aside from the cash awards – which vary in size, with the winner of the Baileys netting £30,000 – prize-winners and shortlisted authors can expect the sort of publicity that you can, literally, not buy (has anyone reading this ever bought a novel based on a Tube advertisement?). When the Baileys shortlist was announced this week, coverage quickly followed not only from literary sources – Foyles, The Bookseller, etc. – but from the global mainstream press: The Telegraph, BBC News, The Independent, The Times of India, RTÉ. And, over the next few days, display stands in bookshops up and down the country will be given over to the front covers of the six nominated books.

Speaking of which, I went in to my local Waterstones this morning: there were several displays of books, but the most prominent, straight ahead on entry, was a table of 'Great New Reads'. I started counting, trying to be inconspicuous. Of the books profiled there, eighteen were by men, and eight by women (one was co-authored; a man and woman). Behind this stand, next to the Karl Ove Knausgård display and the tills, was a smaller table home to the six Baileys prize authors. Were there less women on the 'Great New Reads' display because of the half-dozen represented behind? I suppose there'll be someone willing to argue so, but personally I suspect not.

The Booker shortlists may be improving, but wider literary culture is still skewed in favour of men. My Waterstones anecdote proves little in the grand scheme of things, but it reflects a disparity which more scientific methods have revealed. If you follow the literary press, you may have seen the 2013 VIDA Count figures released back in February; begun in 2010, the Count releases a yearly tally of women whose work is published in, or reviewed by, a series of notable literary magazines. (You can read their methodology here). The 2013 Count, while more encouraging than its predecessors, is still bracing reading: in short, most major journals are still drastically dominated by men. (To give just one close-to-home-example, the London Review of Books reviewed 72 women to 245 men.) It is still undoubtedly the case that, when choosing which novelists to cover, most literary editors will choose male ones. The independent coverage doesn't reflect the shortlists. Editorial responses to VIDA were galling: the reply from Peter Stothard of the TLS, which trotted out the tired line of being "only interested in getting the best review of the most important books", was particularly shameless. For all the infantalising, not-bad-for-a-girl-ness, I remain unconvinced that the Women's Prize gives editors an excuse to compartmentalise fiction by women. I see no evidence that they find an excuse necessary.

And so remedial measures must be taken. And, like most remedial measures, they may seem ugly. The Women's Prize for Fiction is one such measure, and an important one, despite its flaws. (It's worth noting that others, like the Year of Reading Women, which you can follow via the #ReadWomen2014 hashtag, do exist - and have received similar criticism.) The prominence and stature of the Prize, the established tenure of it, forces editors to give up column inches and bookshop owners to set up display stands. It does not replace the main prizes, or prevent women from winning them – clearly, given how many were featured on the Man Booker and Folio shortlists.

The Baileys Prize is not the Paralympics, acknowledging a disadvantage and creating a separate, “equal" category; it recognises not a genuine handicap but a perceived one, and supplements accordingly. It ensures that, in a literary landscape dominated by men, there is one persistent piece of architecture which is guaranteed to make six women novelists visible every year. And this is why, all things considered, it is okay for the Prize to still exist; why they may be forgiven for seeking the biggest sponsors, even if that sponsor has resorted to the 'sex sells' dictum so nakedly that they made glasses of their product look like tits. It is why the panel is not composed solely of the industry representatives who make up, say, the Folio Academy, but celebrity intellectuals: Caitlin Moran, Mary Beard. The Baileys Prize does not exist to allow women to compete; we know that they can do that with the men, and we know that they can win. It exists to keep their competition acknowledged, visible - to give them a table of their own. It is an imperfect response to a nebulous problem, yet for now it serves a key function. For now, we still need it.

I look forward to the day when we don't.